Numerous instances exist where large ships must be rescued in the event of their disablement, such as by loss of power. These instances are invariably urgent. In particular, oil tankers or other ships transporting environmentally sensitive cargoes present especially high risks when in restricted or otherwise hazardous waterways. It is imperative that such distressed ships be brought under control in a timely manner. In certain waterways, depending on the conditions and transit speeds, there may be no more than two minutes before the ship comes to grief.
While such ships are required by law to be escorted by one or more tugboats during transits in confined waterways, the ships generally are not tethered to the tugboats because of the hazards associated with doing so. Such hazards are well known and would require the tugboat to match the speed of the ship at all times. Therefore, it is imperative that a suitable means be provided by which the tugboat can tether to a distressed ship on demand.
One method for rescuing distressed barges is discussed in U.S. Pat. No. 4,242,978 to Fuller. Fuller discloses a hook assembly for retrieving a chain bridle component of a broken towing line used by a tugboat to tow a barge. The tugboat passes back and forth near the barge until the hook of the hook assembly captures one of the links in the chain bridle. The Fuller hook assembly is inadequate for at least three reasons. First, such a chain bridle as described in the Fuller patent is used to recapture a barge whose towing line has parted. A ship that is escorted rather than towed does not have a chain bridge rigged to the ship. Second, such a chain bridle and hook assembly are not strong enough to capture a ship under its own power at speeds up to 12 knots. Third, if the hook of the hook assembly does not capture the chain bridle in the first couple of passes of the tugboat, the danger to the distressed ship is magnified greatly.
Another system recently proposed to rescue distressed ships employs a large articulated arm extending upwardly and rearwardly from the stern of a tugboat. A connection line is coupled at one end to a towing line of the tugboat and at its other end to the free end of the articulating arm. The articulating arm is remote-controlled to connect the connection line to a hookup point on the distressed ship. Such a remote controlled articulating arm is a very expensive addition to each tugboat. In addition, maneuvering the tugboat and the articulating arm simultaneously to connect the connection line to the distressed ship is very complicated and thus highly susceptible to failure.
Due to their inadequacies, the Fuller hook assembly and the remote controlled articulating arm have failed to alleviate the need for a quick and safe method of rescuing distressed ships. As such, the rescue of distressed ships continues to require several crew members of the tugboat and the distressed ship to throw ropes between the vessels and tie the ropes to connection points on the tugboat and the distressed ship. Such methods are very dangerous to the crew members and often require more time than is available to rescue the distressed ship.